• Journal of the Korean Society of Industry Convergence
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• v.20 no.3
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• pp.205-212
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• 2017

This paper focuses on worst-case delay analysis of the time-triggered IEEE 802.15.4 protocol to satisfy the industrial quality-of-service (QoS) performance. The IEEE 802.15.4 protocol is considered to be unsuitable for industrial networks because its medium access control method is contention-based CSMA/CA, which exhibits unstable performance with an unbounded delay distribution under heavy traffic. To avoid these limitations, this paper presents a time-triggered version of the nonbeacon-enabled network of IEEE 802.15.4 that relies on a time division multiplexing access (TDMA) method implemented in the application layer without any modification of specification. The timing analysis of this time-triggered IEEE 802.15.4 was executed, and the worst-case transmission delay was calculated. Based on this analysis, the time-triggered IEEE 802.15.4 is a promising alternative for wireless industrial networking.

• Journal of Korea Multimedia Society
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• v.13 no.2
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• pp.205-215
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• 2010

It is necessary to provide a fast and secure handover for seamless real-time multimedia services based on IEEE 802.11. In this paper, we propose FMIPv6 handoff protocol integrating L2/L3 layer based on IEEE 802.11 WLAN environment. In that, we propose a hierarchical key management scheme and authentication mechanism for protecting the handover signaling messages. The number of connections with AAA server is minimized for the fast handover. It is also compared and analyzed the handover cost with previous method.

• Electronics and Telecommunications Trends
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• v.23 no.3
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• pp.19-28
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• 2008

2007년 3월부터 WFA에서 시작된 "Wi-Fi CERTIFIED(TM)802.11n Draft 2.0" 인증을 통해 현재까지 180가지가 넘는 제품이 출시되고 있는 가운데 이러한 시장의 상황을 반영하듯 여러 매체를 통해 IEEE 802.11n이 2008년 핫이슈로 등장하고 있다. 하지만 차세대무선통신의 기술적인 로드맵을 선도하고 있는 ITU-R WP8F의 IMT-Advanced에서 요구하고 있는 보행시 1Gbps까지 가능하게 하는 기술을 2010년까지 제공한다는 측면에서는 IEEE 802.11n의 성능이 못 미치는 게 사실이며, 이러한 상황을 반영해 IEEE 802.11 내부에서 IEEE 802.11n 후속으로 보행시 Gbps급의 전송 속도를 지원하는 새로운 기술에 대한 표준화 작업에 대한 논의가 꾸준히 있어 왔고, 그 결과 2007년 5월 정식으로 이를 위한 Study Group이 만들어져 작업에 들어갔다. 본 고에서는 이러한 IEEE 802.11에서의 표준화 활동을 중심으로 차세대무선랜에 대한 응용분야, 관련 기술, 표준화 작업 내용에 대해 살펴보고자 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.215-217
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• 2014

본 논문에서는 ns-3 기반의 IEEE 802.15.4 모의 성능 평가에 대해 기술한다. IT 기술의 발달과 함께 차세대 전력망인 '스마트 그리드'가 대두되고 있다. 이에 따라 무선 센서들 간의 통신을 위해 IEEE 802.15.4 표준 기술이 채택되고 있다. IEEE 802.15.4 표준에는 beacon-enabled mode 와 non beacon-enabled mode 두 가지 채널 접근 기법이 존재하지만 특정 기법의 용도와 목적에 대해서는 구체적으로 명시되지 않는다. 따라서 본 논문에서는 스마트 그리드 환경에서 IEEE 802.15.4 의 두 채널 접근 기법의 성능을 시험하고 beacon-enabled mode 와 non beacon-enabled mode 간의 성능 분석을 통해 beacon-enabled mode 의 효용성에 대하여 연구한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.3
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• pp.161-168
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• 2011

This paper provides the performance measurement and analysis of Wireless LAN IEEE 802.11 in a mobile environment. The performances of IEEE802.11b/g and IEEE802.11p designed for Vehicle-to-Vehicle(V2V) communication are measured and analyzed. Diameter of communication and link access time are compared under variation of speed of the vehicle.

• Journal of Digital Contents Society
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• v.13 no.3
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• pp.353-358
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• 2012

Wireless sensor networks consist of resource constraint devices which typically send data measured by sensors attached to the end devices towards a coordinator. The most often used medium access control protocol used in wireless sensor networks is the standard IEEE 802.15.4, where it is wireless standard introduced for low power, low cost wireless communication with moderate data rates. In this paper, we present implementation of both the IEEE 802.15.4 protocol stack and UART interface on the TI CC2530. We show that data via UART of our implemented IEEE 802.15.4 board are transmitted correctly in terms of captured frames.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8A
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• pp.656-663
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• 2005

This paper presents a multi-channel enhancement scheme for the MAC protocol of IEEE 802.15.3 High-rate WPAN (Wireless Personal Area Network). The current MAC protocol of the IEEE 802.15.3 High-rate WPAN is designed for sharing a single channel among DEVs of a piconet; that is, within a single piconet, PNC prevents interference through MAC layer assignment of time slots to other DEVs using time-division multiple access. When the number of DEVs that communicate with each other frequently, is increased in a single WPAN, the size of the superframe becomes inevitably large, and this may result in a significant throughput drop or a failure to provide QoS guarantee. A multi-channel enhancement scheme for the MAC protocol of IEEE 802.15.3 High-rate WPAN is proposed to significantly increase the aguegate throughput and more reliably provide the QoS guarantees in a piconet

• Journal of Internet Computing and Services
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• v.10 no.4
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• pp.213-222
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• 2009

IEEE 802.15.3 HR-WPAN is designed to enable wireless connectivity of high-speed, low-power, low-cost multimedia-capable portable consumer electronic devices. For quality of service, the standard specifies the use of TDMA (Time Division Multiple Access). However, during low contention TDMA gives much lower channel utilization and higher delays than CSMA (Carrier Sensing Multiple Access) because in TDMA, a node can transmit only during its scheduled time slots whereas in CSMA, nodes can transmit at any time as long as there is no contention. By mixing CSMA and TDMA, Hybrid MAC becomes more robust to timing failures, time-varying channel conditions, slot assignment failures and topology changes than a stand-alone TDMA.

• Journal of KIISE:Information Networking
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• v.34 no.3
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• pp.175-185
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• 2007

In IEEE 802.15.4 (Low-Rate Wireless Personal Area Network) specification, a successful reception and validation of a data or MAC command frame can be confirmed with an acknowledgment. However, the specification does not support security for acknowledgment frame; the lack of a MAC covering acknowledgments allows an adversary to forge an acknowledgment for any frame. This paper proposes an identity authentication mechanism at the link layer for acknowledgment frame in IEEE 802.15.4 network. With the proposed mechanism there is only three bits for authentication, which can greatly reduce overhead of device. The encrypted bit stream for identity authentication will be transmitted to device by coordinator within association process. Statistical method and simulation results prove that our mechanism is successful in handling MAC layer attack.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.667-669
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• 2002

IEEE 802.1x는 LAN(Local Area network) 환경에서의 인증을 위해서 IEEE에서 제안한 인증 표준 프로토콜이다 IEEE 802.1x는 token ring, FDDI(Fiber Distributed-Data Interrace), 802.3 등 다양한 802 표준에서 동작할 수 있도록 고안되었다 802.1x는 supplicant와 Authenticator, Authentication Server로 구성된다. 이러한 802.1x의 LAN 환경에서 QoS(Quality of Service)를 보장하기 위해서는 자원 예약 메커니즘이 필요하다. 이러한 자원 예약 메커니즘으로는 RSVP(Resource Resonation Protocol)가 있는데 이것은 유선 네트워크를 위해 설계되었기 때문에 새롭게 수정이 불가피하다. 본 논문에서는 RSVP를 수정 보완하여 WLAN(Wireless LAN)에 맞는 시그널링 프로토콜을 제안한다. 제안한 시그널링 프로토콜을 이용하여 WLAN 에서의 QoS 문제를 해결한다.